1. Field of the Invention
The present invention relates generally to portable biomedical monitoring. More specifically, this invention relates to non-invasive and minimally invasive molecular monitoring, and optionally the implementation of protective feedback measures and remote monitoring through telemetry.
2. Description of the Related Art
Non-invasive transdermal sampling of body fluids has long been a goal in medical research. The notion that valuable diagnostic information comprising the concentrations of key analytes within the bloodstream could be obtained without breaching the skin has spurred many lines of research. With such technology, long-term convenient health monitoring and screening without needles or outpatient care would become a reality: diabetics could monitor blood glucose without drawing blood; markers for microbial, fungal or viral infections could be monitored; and environmental exposure to toxins could be assessed non-invasively.
Biomarkers have been utilized effectively to detect, measure, and assess exposure levels to environmental chemicals deemed hazardous and toxic to human life. The sensitivity of biomarkers allows them to act as early warning indicators to subtle alterations in the environment. Their specificity can be used to establish the nature of the imposing chemical agent, determine exposure level and define a suitable course of action. Environmentally induced diseases affect everyone to one degree or another, however individual susceptibilities can predispose the degree of toxic reaction of one group over another. It is worthwhile noting that in 1996, there were 86,912 cases of pesticide exposures reported to American Association of Poison Centers, of which 26 were fatalities. In particular, individuals in their developmental stages, ranging from the embryonic phase to adolescence, are particularly susceptible to such environmental stresses since key body functions have not matured to a level where they can tolerate, process and handle such exposures. The use of biomarkers for determination of children's environmental health will allow for the early detection of toxins, prevention of impairment in their physical condition, and determine a course of treatment for children who have been exposed to a toxic environment.
Especially important in the field of pediatrics is the use of health evaluation tools that are minimally intrusive.
Many transdermal sampling techniques have been reported, but all to date suffer from one or more serious drawbacks. Conventional techniques have disadvantages of being grossly invasive (and potentially injurious) and sweat or interstitial fluid dependent, except for the: passive, non-sweat dependent transdermal analyte collection and detection techniques.
One approach to transdermal sampling has employed the collection of sweat. For example, M. Philips and M. H. McAloon, Alcohol Clin. Exp. Res. 4 391 (1980) disclose an absorbent patch which is a salt-impregnated, cellulose pad under an occlusive, adhesive cover. However, such a method of transdermal sampling is dependent upon the sweat rate, requires sweat extraction by centrifugation, and calls for external chemical analysis. S. Balabanova and E. Schneider, Beitr. Gerichtl, Med 48, 45 (1990), disclose Pilocarpine-induced sweat secretion, but the system requires Iontophoresis-induced infusion of pilocarpine and analyte dilution. U.S. Pat. No. 5,203,327, issued to Schoendorfer, et al., discloses an absorbent pad under a water vapor-permeable, occlusive, adhesive cover, but the system is sweat rate dependent and requires chemical extraction and external chemical analysis. F. P. Smith and D. A. Kidwell, Forensic Sci. Int. 83, 179 (1996), discloses a cotton sweat wipe, but this system is sweat volume-dependent and requires extraction and external chemical analysis. G. L. Henderson and B. K. Wilson, Res. Commun. Chem. Pathol. Pharmacol., 5, 1 (1973), discloses the collection of liquid sweat following exercise, but the system requires vigorous exercise, is sweat volume-dependent, and requires extraction and external chemical analysis.
C. C. Peck, D. P. Conner, et al., Skin Pharmacol., 1, 14 (1988), discloses a gel with an analyte binding reservoir under an occlusive adhesive cover. However, this reference requires extraction and external chemical analysis.
U.S. Pat. No. 4,909,256, issued to Peck discloses a dry binding reservoir under an occlusive adhesive cover. However, this reference requires extraction and external chemical analysis.
U.S. Pat. No. 4,821,733, issued to Peck discloses a collection and detection system under an occlusive adhesive cover. However, this reference requires highly sensitive detection components.
U.S. Pat. No. 4,775,361, issued to Jacques discloses enhanced migration of analyte to a skin surface. However, this reference requires introduction of light energy into the body.
U.S. Pat. No. 5,362,307, issued to Guy discloses iontophoretic enhanced analyte collection across skin. However, this reference requires the introduction of electrical energy into the body.
U.S. Pat. No. 5,722,397, issued to Eppstein discloses ultrasound enhanced analyte collection across skin. However, this reference requires the introduction of sonic energy and chemicals into the body.
U.S. Pat. No. 5,885,211, issued to Eppstein, discloses micropore formation using heated water vapor, physical lancet, sonic energy, high pressure jet of fluid, or electricity. However, this reference requires puncture of the skin using heat, sonic, or electrical energy, physical or hydraulic force.
The website www.spectrx.com discloses the application of vacuum to laser-induced dermal micropores for harvesting of interstitial fluid. However, this reference requires introduction of sonic energy into body, as well as physical energy to harvest interstitial fluid and may cause an inflammatory reaction.
There is, therefore, a need within the transdermal sampling field for a minimally invasive sampling technique and apparatus suitable for rapid, inexpensive, unobtrusive, and pain-free monitoring of important biomedical markers and environmental toxin exposure. These properties and advantages of the present invention will become apparent to those of skill in the art upon reading the following disclosure.